Clamping device for tapered propeller blades



Oct. 3, 1933. C E I swarms mavxcs FOR TAPERED PROPELLER BLADES 2 Sheets-Sheet, 1

m! Q .vvanNl mm 7//// a 1 BE A 3 aw E .1 Q 9m 9w 7714K". vmm' Hi4 A TTORNE Y3 Patented Oct. 3, 1933 UNITED STATES CLAMPING DEVICE FOR TAPERED PROPELLER, BLADES James H. McKee, Pittsburgh, Pa., assignor to Pittsburgh Screw and Bolt Corporation, a corporation of Pennsylvania Application April 5, 1932. Serial no. 603,258\

12 Claims. (Cl. 266-4) This invention relates to the hardening and tempering of hollow steel propeller blades, and more particularly to a clamping device that shall effectually prevent warping and distortion of 5 hollow steel propeller blades during some part or all of the heat treating processes to .which such blades are subjected to put them in finished form.

In the manufacture of hollow propellerblades of the type described in United States Letters Patent No. 1,713,500, granted to Thomas A. Dicks on the fourteenth day of May, 1929, the adjacent edges of two relatively thin tapered sheets are joined together by welding to produce a hollow steel blade in which each succeeding transverse section decreases gradually in thickness from the shank to the tip end thereof. Such blades have a decided tendency to become distorted after the hardening and tempering process on account of one sheet cooling more rapidly than the other. oftentimes such a blade becomes so warped or the tip end thereof becomes so curled that if the blade is not scrapped as a result of such distortion, considerable time must be spent in straightening the blade before it is in condition for use, thereby not only increasing the manufacturing costs of such blades but also making it impossible to produce such blades commercially.

Attempts have been made heretofore to prevent this type of blade from warping as it is cooling after heat treating by placing it in a twopart clamping device, each part of which had a cavity therein which, when the device was assembled, conformed in shape to the curvature of the blade. Such a device, however, was not satisfactory because, in order to receive the heat treated blade, the cavities in the clamping members had to be as large as the expanded blade and as a result, as soon as the blade started to contract when cooling, it shrank away from the sides of the clamping device and became so loose that warping of the blade was permitted.

One object of my invention is to provide a clamping apparatus for supporting tapered hollow propeller blades while cooling after heat treatment, which will firmly engage the blade at all times and prevent it from being distorted or warped.

Another object of my invention is to provide 50 an apparatus for supporting heat treated tapered hollow propeller blades during the cooling steps which will follow up the contraction or shrinkage of the cooling blade and exert a clamping actionv 5 on the blade at all times.

supporting tapered hollow propeller blades during the quenching operation following heat treatment in which succeeding transverse sections of theblades will be engaged and held.

A still further object is to provide a clamping device for tapered hollow propeller blades which will engage only the solid edges of the blade and will not crush'or distort the sheets forming the cambers of the blade.

These and other objects which will be made readily apparent to those skilled in this particular art are accomplished by means of this invention, one .embodiment of which is described in thefollowing specification and illustrated in the accompanying drawings, wherein:

Figure 1 is a top plan view of my improved clamping apparatus;

Fig. 2 is a view in side elevation of the clamping device having one end thereof broken away for convenience of illustration;

Fig. 3 is a view in vertical section taken on line IIIIII of Figure 1;

Fig. 4 is a view in end elevation of the device having portions thereof broken away for clearness;

Fig. 5 is a top plan view of the blade receiving member having a blade positioned therein, and having a removable tip portion;

Fig. '6 is a view in side elevation of the blade receiving member;

Fig. 7 is a top plan view of a tip portion which may be used with the blade supporting member,

and

Figs. 8 to 18, inclusive, are sectional views of the blade supporting member taken on lines VIII-VIII, IX--IX, X--X; XI-Xl, IflI-XII, X[IIX[II, XIV-X[V, XV-XV, and XVI-XVI of Fig. 6, and XVII-XVII, XVIII-XV]IE of Figure 7, respectively.

In general my improved device for holding a heated propeller blade straight while it is being hardened by quenching, or tempered by cooling in air to prevent it from being warped or distorted, comprises a blade supporting member shaped to conform .to the curvature of a pro-- peller-blade on which a heat treated propeller blade is securely held by a series of transversely extending clamping members. These clamping members are spaced longitudinally above the blade receiving member and are held in blade engaging position under a continuing pressure so that as the blade contracts and shrinks in length, these clamping members will progres-- sively engage succeeding transverse bladesections of decreasing thickness and hold the blade ing a concave perforated surface 12 spaced above a the base 10 on which a propeller blade 30 is adapted to be positioned. The member 11 is made slightly shorter than the length of a standard propeller blade and the tip of the blade is supported on a member 13, removably mounted on the base 10 and having a concave perforated surface 14 which, when the member is in position on the base, forms a continuation of the surface 12 in the member 11. The surfaces 12 and 14 are shaped to conform to the curvature of a propeller blade and in order that the device may be used with any length of blade, the member 13 may be removed and another member 13 (Fig. '7) having a surface 14' similar in construction to the surface 14 may be secured to the base 10.

Extending upwardly from the base 10 at spaced intervals along its length and on each side of the member 11 are rods 15 the tops of which are tied together by members 16 extending transversely across the base 10 and bolted to the rods 15. Each of these members 16 supports a cylinder 17 having a vertically movable piston 18 therein. Each of the pistons 18 has a piston rod 19 secured thereto which extends through an opening 20 in the bottom of the cylinder 17 and is connected to a member 21 slidably mounted between each set of opposed rods 15. In order that the members 21 will slide freely on the rods 15, the ends of the members .21 terminate in elongated members 22 having curved surfaces which partially embrace the rods 15 and form bearings on the members 21. These bearings permit the members 21 to slide freely on the opposite rods 15.

Each of the cross sliding members 21 has a member or yoke 23 pivoted thereto which, when the sliding members are in their lowermost position, engage the blade 30 supported on the surfaces 12. and 14 and clamp it thereagainst. The yokes 23 depending from the members 21 disposed above that portion of the member 11 which supports the shank of the blade are semi-circular in shape so that when in blade-engaging position these yokes encircle the shank of the blade (Fig. 4) while the yokes depending from the members 21 disposed over the hollow body. of the blade are so shaped that only the edges of the blade (Fig. 3) are engaged thereby and injury to or crushing of the blade is prevented.

In order to lower the yokes 23 into clamping position and to force them to follow up and engage succeeding portions of the blade, compressed air is admitted to the top of each of the cylinders 1'7, through pipes 24 connected to a pipe 25 which leads to a suitable source of compressed air supply (not shown). The pistons 18 are moved upwardly in the cylinders 1'1 to release theyokes 23 by compressed air delivered to the bottom of each of the cylinders 1'1 through a pipe 26 connected to a pipe 27 w'h ich also leads to a suitable source of compressed airsupply.

In operation, when the blade 30 has beenheated to hardening temperature, it is .placed on the surfaces 12 and 14 of the members 11 and '13 and if the tip of the blade extends substantially beyond the last yoke 23, a plate is so placed over the tip end of the blade that the end thereof extends underneath the yoke 23 'adjacent the end of the blade. Air is then delivered to the tops of the cylinders 1'? through the pipes 24 which forces the pistons 18 downwardly and causes the yokes 23 to clamp around the shank of the blade and ,to engage the edges of the hollow portion of the blade so that it is'firmly pressed against the members 11 and 13.

As the blade in the clamping device cools, it contracts or shinks so that it decreases in length, and moves lengthwise on the member 12 at right angles to the clamping yokes 23 and since the shank end of the blade is firmly held in the device, it is apparent that as the blade shrinks, thinner portions thereof are progressively positioned underneath the yokes engaging the edges of the blade. Since each of the yokes 23 over the hollow portion of the blade is held against the edges thereof by a continuing pressure, it follows that as the thinner portions of the blade are moved under these yokes, the pistons 18 will be moved downwardly and cause the yokes to firmly engage these succeeding thinner sections of the blade and clamp them against the member .11 whereby the blade is firmly held against the surface 12 at all times and warping, curling, or distortion of the blade is prevented.

In order that sufficient pressure will be applied to the relatively thick shank portion of the blade to hold it firmly against the surface 12, two of the tie members 16 disposed over that portion of the surface 12 shaped to receive the shank of the blade 30 are provided with twin cylinders.

After the blade has cooled, air. is delivered to the cylinders 17 through the pipes 26 which forces the pistons 18 upwardly and raises the yokes 23 from engagement with the edges of the blade 30'; The blade is then removed and another heated blade is placed in the clamping device.

As the yokes 23 are positioned at spaced intervals along the length of the blade and as the majority of these yokes engage only the edges of the upper face or camber of the blade, it is readily apparent that this face of the blade is substantially exposed to a cooling medium. So that both faces or cambers of the blade will cool at substantially the same rate of speed, I prefer to perforate the surfaces 12 and 14, whereby the lower face of the blade will also be exposed to the cooling medium.

It isreadilyapparent from the foregoing description that with my improved clamping device the blade will be firmly held therein at all device may be used to prevent the blade from being distorted as it is cooled either in a quench or in air. When it is used to hold the blade straight during the quenching, the heat treated blade is placed in the device and both are then submerged in the quenching liquid.

. While I have illustrated my clamping device as being operated with compressed air, it is understood that any type'of fluid'pressure may be used to operate the pistons without departing from my invention. It is also understood that while I have described one embodiment of my invention, certain modifications and the like may be made therein without departing from the spirit of my invention or the scope of the appended claims.

What I claim as new and. desire to secure by Letters Patent is:

1, Apparatus for holding hollow propeller blades to prevent warping after tempering and hardening operations, comprising a member having a perforated surface shaped to conform to one face of a propeller blade, and means extending transversely across said member at spaced intervals for holding a blade firmly against said perforated surface at all times regardless of the shrinkage of the blade.

2. An apparatus for holding heat treated propeller blades to prevent warping during cooling, comprising a perforated base plate shaped to conform in contour to one camber of a propeller blade, members extending transversely of said plate adapted to engage the edges of a blade when positioned on said plate, and means for moving said members into blade engaging position and for holding them against the edges of said blade at all times regardless of the shrinkage therein.

3. A clamping fixture for use in heat treating and tempering tapered propeller blades comprising a perforated bed plate shaped to conform to one camber of a tapered propeller blade, a series of spaced yokes extending transversely of said bed plate and adapted to engage the edges of a blade placed thereon, and pressure responsive means for continuously forcing said yokes against progressively smaller portions of said blade as it contracts and moves relative to the bed plate. 4. A clamping fixture for use in heat treating and temperingtubular propeller blades comprising a member for supporting a propeller blade having a surface shaped to conform to one camber thereof, means extending transversely of said plate for engaging the edges of said blade at spaced intervals along its length and pressing it against said member, and means for yieldingly holding said pressing means against the edges of said blade whereby successive thinner portions of said blade are engaged by said pressing means and curling or warping of the blade is prevented.

5. A clamping fixture for use in heat treating tubular propeller blades, comprising aframe, a perforated plate carried on said frame and shaped to conform to one camber of a propeller blade, means extending transversely of said plate at spaced intervals along its length for clamping a blade against said plate, andpressure responsive means supported on said frame above said plate for continuously forcing said clamping means against said blade as it shrinks and moves at right angles to the said clamping means, the clamping means adjacent the shank end of the blade being semi-circular in shape to partially encircle the blade and the remaining clamping means being shaped to engage only the solid edges of the blade.

6. A clamping fixture for receiving tapered pro peller blades adapted to shrink-on cooling, comprising a frame, a plate carried on said frame and shaped to support a propeller blade thereon, a series of pressure-responsive mechanisms supported on said frame above said plate, a yoke depending from each of said pressure responsive mechanisms and extending transversely of said blade, and means for actuating said pressure responsive mechanisms to move said against said plate.

7. A clamping flxture'for receiving heated tapered propeller blades adapted to contract on cooling, comprising a plate shaped to receive and yokes intoengagement with said blade to hold it firmly.

support a propeller blade thereon, a series of spaced yokes extending transversely of said plate and shaped to engage only the edges of the blade, and pressure actuated mechanisms associated with said yokes for moving the same into blade-engaging position and holding the yokes against the edges of the blade as it moves at right angles thereto due to contraction in cooling.

8. A clamping device for use in heat treating and tempering tubular propeller blades comprising a frame, a bed base plate having a perforated surface shaped to conform to one camber of a propeller blade, a seriesof cylinders supported on said frame above said plate, each of said cylinders having a piston movable therein, a yoke operatively connected to each of said pistons and extending transversely of said plate, and means for actuating said pistons to move said yokes into clamping engagement with a blade positioned on "movable in each of said cylinders, a piston rod connected to each of the pistons, a yoke pivotally connected to the end of each of the piston rods,

and means for actuating said pistons.

10. A clamping device for use in heat treating and tempering tubular propeller blades, comprising a frame, a plate mounted on said frame having a perforated surface shaped to conform to one camber of a propeller blade, a series of vertically movable spaced yokes extending transversely of said plate, and pressure actuated mechanism for moving each of said yokes into blade engaging position, the yokes adapted to engage the shank end of said blade being semi-circular in shape, the yokes adapted to engage the remaining portions of said blade being shaped to engage only the solid edges thereof.

11. A clamping device for use in heat treating and tempering tubular propeller blades comprising a plate having a surface shaped to receive and support a propeller blade, a series of vertically sliding, spaced yokes extending transversely of said plate, some of said yokes being shaped to, encircle the shank end of the blade and the remainder of said yokes being shaped to engage only the edges of the blade and pressure actuated mechanisms associated with said yokes for moving the same into blade engaging position and holding the yokes against progressively thinner sections of said blade.

12. Apparatus of the character described comprising a support for a propeller blade having a and independently. actuated members extending surface conforming in shape to one face thereof,

transversely of said surface adapted to exert a pressure on the opposite edges of the blade and clamp it on thesupport, said members maintaining a substantially constant pressure on the blade edges whereby as the blade contracts lengthwise while cooling after heat treatment, successive edge portions of the blade are engaged thereby and the blade is held straight and prevented from' warping.

JAIMES H. MCKEE.

CERTIFICATE OF CORRECTION.

Patent No. 1,928,818. October 3, 1933.

JAMES H. 'McKEE.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 3, line 86, claim 8, strike out the word "base" and after "plate" insert the words mounted on said'frame; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Off- Signed and sealed this 21st day of November, A. D. 1933.

' F. M. Hopkins (Seal) Acting Commissioner of Patents. 

